Re: [PATCH 4.19 17/36] cxgb4: use correct type for all-mask IP address comparison

Rahul Lakkireddy
2020-07-08T12:50:19Z

On Tuesday, July 07/07/20, 2020 at 23:33:26 +0200, Pavel Machek wrote:
> Hi!
>
> > From: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
> >
> > [ Upstream commit f286dd8eaad5a2758750f407ab079298e0bcc8a5 ]
> >
> > Use correct type to check for all-mask exact match IP addresses.
> >
> > Fixes following sparse warnings due to big endian value checks
> > against 0xffffffff in is_addr_all_mask():
> > cxgb4_filter.c:977:25: warning: restricted __be32 degrades to integer
> > cxgb4_filter.c:983:37: warning: restricted __be32 degrades to integer
> > cxgb4_filter.c:984:37: warning: restricted __be32 degrades to integer
> > cxgb4_filter.c:985:37: warning: restricted __be32 degrades to integer
> > cxgb4_filter.c:986:37: warning: restricted __be32 degrades to integer
>
> > diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_filter.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_filter.c
> > index 7dddb9e748b81..86745f33a252d 100644
> > --- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_filter.c
> > +++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_filter.c
> > @@ -810,16 +810,16 @@ static bool is_addr_all_mask(u8 *ipmask, int family)
> > struct in_addr *addr;
> >
> > addr = (struct in_addr *)ipmask;
> > - if (addr->s_addr == 0xffffffff)
> > + if (ntohl(addr->s_addr) == 0xffffffff)
>
> Endianity does not really matter for ~0, but can compiler figure it
> out?
>
> would it be better to do these tests as
>
> if (foo == htonl(0xffffffff))
>
> to make it clear to the compiler?
>

Sure, I'll update all checks to follow above approach. Will send a
patch.

>
> > } else if (family == AF_INET6) {
> > struct in6_addr *addr6;
> >
> > addr6 = (struct in6_addr *)ipmask;
> > - if (addr6->s6_addr32[0] == 0xffffffff &&
> > - addr6->s6_addr32[1] == 0xffffffff &&
> > - addr6->s6_addr32[2] == 0xffffffff &&
> > - addr6->s6_addr32[3] == 0xffffffff)
> > + if (ntohl(addr6->s6_addr32[0]) == 0xffffffff &&
> > + ntohl(addr6->s6_addr32[1]) == 0xffffffff &&
> > + ntohl(addr6->s6_addr32[2]) == 0xffffffff &&
> > + ntohl(addr6->s6_addr32[3]) == 0xffffffff)
> > return true;
> > }
> > return false;
>

Thanks,
Rahul